Hi All,
Just kicking some ideas around for the feed on my lathe in that as I have a spare stepper motor I think i can connect it to the feed screw and save the messing with the gears.
On my chineses lathe the fine feed is set by setting the gears to a very fine pitch 0.1mm which is not that fine but it will not go any lower.
So my question is if I buy a simple driver box as per http://www.arceurotrade.co.uk/en-gb/dept_181.html a 3A Bi-Polar Stepper Motor Driver near the bottom of the page, can I supply the pulses with a simple pulse generator and change direction with just switches etc.
I'm not sure what the PC and mach3 deliver to the driver.
So any info greatly appreciated.

Peter

John Stevenson

02-05-2008, 05:27 PM

Peter,
Get hold of issue 118 and 119 of model Engineers workshop.
David Haythornthwaite described such a system using this same drive for the Wabeco Milling Machine.

.

ptjw7uk

02-06-2008, 08:09 AM

Thanks John
I will see if I have those copies.
Peter

lazlo

02-06-2008, 09:42 AM

Get hold of issue 118 and 119 of model Engineers workshop. David Haythornthwaite described such a system using this same drive for the Wabeco Milling Machine.

Did he build a complete electronic leadscrew?

Does anyone have a copy of that article?

Ryobiguy

02-06-2008, 12:30 PM

Get the stepper and mount it up on the lathe. The PC or other controller needs to supply step and direction signals. There may also be a simple way of adding a spindle sensor, so you can get actual feed rates instead of just a power feed that stays constant when the spindle speed changes.

Sign up for the Yahoo Electronic leadscrew group, they've almost got a shipping product if you don't want to use a PC: http://tech.groups.yahoo.com/group/E-LeadScrew/

On my machine, I added a stepper for the lead-screw and a gear tooth sensor for the spindle: http://www.fricktion.net/~mfrick/gearsensor/index.html
Then I wrote a module for EMC^2 (a Linux CNC program) that does a simple job of emulating a manual lathe's gearing and threading dial functionality. Some day I'll release it to the general public.

Now I don't need to acquire change gears, I can change feeds on the fly, and I can also do threading at any pitch I want.

BobWarfield

02-06-2008, 06:10 PM

Long ago, in a galaxy far away, I started down this path. I posted to a lot of boards, and I got several people fired up enough to start that E-Leadscrew group on Yahoo.

My theory was that I would go in stages. I wanted to start out with a pulser board so I could control my leadscrew not for threading, but simply as a continuously variable power feed built with a stepper, a GeckoDrive, and a simple pulser board with analog "controls":

http://www.cnccookbook.com/MTManualStepperController.htm

Some notes on that page:

- I never built or tested those circuits and I am no Electrical Engineer (though I took courses long ago in college). Somebody like Lazlo can comment on the "right" way to do it, but many saw the designs including some from E-Leadscrew and suggested they would work.

- I wanted something that would allow both the manual or CNC control. You'll note connections for a breakout board. You may or may not care about that, but I thought it a cool feature.

- The controls were going to be On/Off, Forward/Reverse, and a speed pot.

- I would rely on CNC to thread, so this is not an E-Leadscrew.

As time went on, I began to imagine it would be easy to embed an E-Leadscrew in the Shumatech DRO design and that this would be very cool. It wouldn't take much logic and very few outboard components.

I wasn't able to interest the Shumatech guy (who later bowed out of the DRO too), but I thought it would make a cool companion to that DRO and a similar complexity project, so I did a mocked panel design to match the Shumatech:

http://www.cnccookbook.com/MTLatheElecLeadMockDocs.htm

Now let's make the long story short. I still think the dual mode manual/CNC stepper pulser would be a cool feature. However, every boy and his dog was telling me that once you built all this stuff, full CNC was very little more work, infinitely more useful, and just as easy to learn. Eventually I had done enough with it to conclude they were right.

Hence I have not gone further with all this and moved on to doing a CNC conversion on my lathe.